1.1.1.4 Class 3 – Conditional State Transition and State Output (Moore State Machine)

In Class 3 state machines, the next-state, $X$ , is determined by both the present state and the inputs, $Q$ , while the outputs, $I$ , are determined solely by the present state. The portion of the general state machine relevant to Class 3 is shown with solid lines in Figure 1-5.

Unlike Class 2 state machines, which follow a specific sequence of states, Class 3 state machines can choose alternate state sequences depending on the previous state and input combination.

The Class 3 state machine is more commonly known as the Moore State Machine. The next-state and output expressions can be represented as follows:

Equation 1-7. Class 3 Next-State Expression

X \leftarrow g [X, Q]

Equation 1-8. Class 3 Output Expression

I = f [X]

Important: Class 3 state machines can implement any algorithm that a Class 4 state machine can. However, using a Class 4 state machine often requires fewer states to achieve the same behavior.

Figure 1-5. General Class 3 State Machine – Moore State Machine